Hi, RANGER1 ... thanks ...
been busy around house and family ... one son with his family moved into new house (rebuild old one) and there were never ending requests for help since spring time ... another son moved back to our house ... again repairs, improvements, paintings ... 12 hours a day shift ... and still not finished, but winter is coming and some works we have to postpone until next year spring or summer ....


Quote Originally Posted by RANGER1 View Post
Josip,
Good to see you back, as has been awhile.
Never heard of this scenario myself as a common thing.
Pressures should never be higher than 10-15% of relief valve setting, that's where compressor trip points should be without exception.
When valves are tested it should be checked for zero leakage at that pressure to check it's security after relief pressure set.
Maybe poor quality reliefs?
Rupture discs are good if multiple reliefs go into common header to see which one let go in event of release that should never happen.
Also good for ***** or synthetic refrigerants to prevent loss of refrigerant.
I also think your old school ammonia sensor on relief vent is best, also oil in "s" trap is good as well.

It is not a common thing ... more exception ... can be effect due to lack of good relief valves pressure test .... poor quality reliefs ... for some reason running plant at high discharge pressure ... some reliefs are equipped with handle for manual operation for check and maybe not close tight after check or just be opened by accident during installation without note to supervisor (to retest relief) ... new plant ... maybe young operators without a lot of experience ... etc .. kind of Murphy's law ...

... as I remember happened to me only on two plants (each with only one relief passing, but all were connected to common header going over roof and not quite good for access) so it is not so common but can happen ...

Best regards, Josip